Saturday, August 27, 2016

Ramble Report August 25 2016


Today's Ramble was lead by Linda Chafin.
Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don unless otherwise credited.)
Today's post was written by Dale Hoyt.

No. attending: 20

Today's reading:
Bob Ambrose treated us to another of his poems:

Saturday, August 20, 2016

Ramble Report August 18 2016



Today's Ramble was lead by Dale Hoyt.

Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don.)

Today's post was written by Dale Hoyt.



No. Attendees: 22

Today's reading was supplied by Rosemary. She intends to ramble in England in the near future, so she read a short history of the British Ramblers Association, followed by Bill Bryson's account of the famous (in Great Britain) Kinder Scout civil disobedience in his book, The Road to Little Dribbling:


Friday, August 12, 2016

Ramble Report August 11 2016



Today's Ramble was lead by Linda Chafin.

Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don.)

Today's post was written by Dale Hoyt.

Number of attendees: 24

Announcements:
 
Thank you, Ed and Sue!!


Find the item you've been longing for!
Help out the SBGG!

Today's reading: Linda read a poem from The Writer's Almanac: From a Country Overlooked, by Tom Hennen:


Friday, August 5, 2016

Ramble Report August 4 2016



Today's Ramble was lead by Dale Hoyt.
Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don.)
Today's post was written by Dale Hoyt.

Announcements:
The State Botanical Garden of Georgia has a new weather station that is internet connected. You can get up-to-the-minute weather at the Garden and a forecast. Visit the website at: https://athensclarke.weatherstem.com/sbg
When at the above website click on the "Handout" menu item to discover the many other features available: Twitter, Facebook, automated phone weather information, etc. It's a wealth of weather information you can explore!

Our fellow Rambler, Bob Ambrose, has published his new book of poetry: Journey to Embarkation, poems written mostly before he began writing about nature. Bob says that his book will be available at Avid Books beginning Friday, August 5. He will also have a few copies that you can purchase from him at our next Ramble. (The book is also available online from two sources: Amazon and Parson's Porch & Book Publishing Co.)

Number of attendees: 24

Warm-blooded Bumblebees



Humans and most other mammals are called "warm-blooded," meaning that our body temperature arises from heat generated within our bodies. All our cells are actively engaged in chemical reactions that generate heat. They are like the engine of a car that runs all the time. Even at idol the engine consumes gasoline and produces carbon dioxide and heat. Like the automobile engine we consume fuel (carbohydrates, fats), burn it and use the resulting energy in several ways: 1)to grow, repair and replace tissues, 2) store energy (as carbohydrate and fat), 3) keep our body temperature constant (98.6 F°), and 4) move about our environment. The cells of a "cold-blooded" animal do the same things, but they don't produce enough energy to raise body temperature above that of its surroundings. The only way a cold-blooded animal can raise its temperature is by finding warmer surroundings like basking in the sun. In fact, an insect sitting in the sunlight may have a higher body temperature than a human. Because of this it is better to use the terms ectothermic and endothermic in place of cold-blooded and warm-blooded. (Ectothermic means heat is obtained from external sources; endothermic meand heat is generated from internal chemical reactions.)

Bumblebees are partially endothermic. They can generate enough heat to fly if the temperature of their environment is not too cold. They can accomplish this feat because of three features: 1) the way their body fluid circulates, 2) their powerful flight muscles and 3) the way their abdomen is attached to their thorax.

Let's begin on a cold morning. The bee contracts all its flight muscles simultaneously. The muscles that move the wings up are straining against the muscles that move the wings down, so the wings don't flap, they just shudder a little. It's an isometric exercise – muscle tension without work. It looks like they might be shivering. The contraction of these opposing muscles generates heat and the thorax begins to warms up. The hairs that densely cover the bumblebee's thorax act as insulation, so some of this heat is retained and warms the body fluid that bathes the organs in the thorax.

Insects have an "open" circulatory system, meaning that they lack circulatory vessels like arteries and veins and their tissues are simply bathed in a fluid (called hemolymph, the insect's blood) that is slowly circulated. The circulation of hemolymph is accomplished by a heart, which is a simple muscular tube that runs from the abdomen through the thorax to the head. The heart beats with a wave of contractions that push the hemolymph inside the tube forward toward the head end. (This is like our esophagus works when we swallow food or water.) The heart keeps pushing hemolymph forward so the hemolymph in the head end is forced to move back toward the abdomen. So bee blood slowly flows from the head back through the thorax into the abdomen and then gets picked up by the heart and pumped forward to the head again. That's how the blood gets circulated.

The blood vessel in the thorax runs between the flight muscles and is warmed by the heat produced when they contract.

Now the way the bee body is built becomes important. The thorax and abdomen are only narrowly connected, like a wasp waist. (You have to have a bee in hand to see this – the thorax and abdomen look like they are broadly connected, but they really aren't.) The heart must go through this narrow connection and all the hemolymph in the head and thorax must flow through the same connection as it moves from the head back to the abdomen. The blood coming from the head and throax has been warmed by its contact with the contracting flight muscles. The hemolymph in the heart that is coming from the abdomen is cooler and it is warmed by the warmer hemolymph moving through the connection between thorax and abdomen. This heating of incoming hemolymph preserves the higher temperature in the thorax, and, as the flight muscles continue to contract, the thoracic temperature rises until the flight temperature is reached. This mechanism is called a counter current heat exchange and the principle is used in many mechanical devices, e.g., air conditioners, to improve their performance.

If a bee starts early in the morning when the temperature is in the low 70s it won't be able to fly. It must reach a minimum of 86 degrees F before its flight muscles can operate with the necessary speed of contraction. Once that temperature is reached it can fly away. (The temperature in the thorax can reach as high as 104 degrees F or more – the equivalent of a delirious fever for a human. And bees are supposed to be cold blooded!

Tuesday, August 2, 2016

Ramble Report July 28 2016



Today's Ramble was lead by Linda Chafin and written by Linda with note-taking assistance by Sue Wilde. We are indebted again to Rosemary Woodel for providing the photographs that accompany this post.

Announcements: Bob Ambrose shared the publication of his new book of poetry, Journey to Embarkation, poems written mostly before he began writing about nature. He read a poem for us, The Night Music of San Rafael de Guatuso, which was set in Costa Rica and featured the call of the Dusky Nightjar, a bird closely related to and sounding much like our own Whip-poor-will. Bob notes that his book is also available online from two sources: Amazon and Parson's Porch & Book Publishing Co. (Bob will also have some copies available to Ramblers at a reduced cost.)

23 people appeared for the Ramble today. 

Today's route: We wandered down the Orange Trail Spur to the floodplain, turned right at the base of the slope, and entered the Powerline Right-of-Way.